Our Kelp Restoration Journey
Our four year partnership with Seaforester to restore kelp forests along the Portuguese coast has been a journey of true exploration. While we set out to restore these vital ecosystems, we also aimed to test and refine the science behind coastal restoration.
Here is a look at what we learned along the way. Get strapped in for a long update!
Our Experimental Findings
We tested three methodologies each teaching us something about the challenging conditions of restoring kelp in the Atlantic ocean:
Spore Bag Technique (2021)
Our first trial with SeaForester aimed to colonise bedrock by releasing spores from captured reproductive kelp patches. Unfortunately, this method resulted in no kelp establishment. While disappointing, it provided a clear indicator that this technique is not effective in these specific conditions, preventing future wasted effort. As such, we’re working on publishing our findings in a scientific paper.
Green Gravel Technique (2023-2024)
Seeing promising results in Norwegian fjords by the Institute of Marine Research, we set out to test this method of deploying nursery grown ‘green gravel’ kelp and its scalability potential in Portugal. Our first attempt in Cascais and Peniche showed positive signs in 2023, with some of our kelp surviving the open ocean over winter and growing to 30cm.
Based on this trial, we started testing if larger deployments would establish the densities kelp need to become self-sustaining. However, in 2024, our deployment (33,600 gravel stones) at Guia Reef saw no survival. We suspect high herbivory pressure and rough sea conditions prevented kelp from establishing and attaching to the reef, highlighting that site and timing selection are as critical as the technique itself. The challenges of projects done in high-energy coastlines was discussed in this scientific article to which SeaForester contributed.
We also ran a trial at a deeper site (19,740 stones) targeting an area where historical kelp forests of Laminaria ochroleuca once thrived before severe depletion from intensive net and trawling fisheries. Monitoring revealed 10 individuals though we couldn't confirm if they were from our deployment. A key learning was that more robust kelp from the nursery could be needed but encouragingly, the site shows great potential with low grazer abundance of sea urchins and existing dense kelp patches, making it a strong candidate for future work.
Sea-socks Technique (2024)
This trial showed that enclosing kelp-seeded rocks in a biodegradable mesh can prevent the rock movement that occurs after deployment, movement that otherwise hinders kelp settlement and complicates monitoring. Monitoring revealed that 10 out of the 12 mesh bags were still present, however, no kelp growth occurred. It seems likely that the netting material strands were too thin and cut into the young kelp so it is probably worth testing a different material such as coconut fiber or cotton.
What This Means
We chose to focus on kelp restoration because we saw huge potential impact in innovating and learning in this space and because large-scale kelp restoration won't become a reality unless we start learning by doing. Science rarely moves in a straight line, but as long as we learn from every "failure," we keep making progress. Had we not run these trials, many questions would still be pure speculation: the pros and cons of different deployment techniques, the practicalities of growing and deploying kelp at scale, and the barriers to kelp establishment at different sites. Even if the final approach to kelp restoration in Portugal ends up looking quite different from what we're doing now, it will be built on these learnings.
Looking Ahead
For now, we have decided not to pursue further kelp-related projects as we focus on growing our Rewilding Hubs, running our Innovation Programme and continuing to support a diversity of ongoing projects around the world. In the meantime, we trust the capable hands of the SeaForester team to continue pursuing this work at the pace the science demands. To follow their journey, be sure to check out their website and social media channels.
Kelp has earned a place in our hearts, so we may very well end up diving back into this world in the future.
If you want to learn more, check out the vlog above. There will also be a future video to round up the project on our main YouTube channel.